Sealing arrangement for enclosed chamber

ABSTRACT

In an environmental chamber provided with a plurality of dynamic clearance seals disposed therein to enable the transferance of a web of material, i.e., film, through a separating wall without substantial leakage or contamination. Slotted ports offset 90* with respect to one another are disposed in the chamber entrance and exit to cooperate with corresponding clearance passages formed interior of the chamber and permits passage of the web material into more than one environment without contamination.

United States Patent [191 Seminski [451 Apr. 30, 1974 SEALING ARRANGEMENT FOR ENCLOSED CHAMBER [75] Inventor: Robert B. Seminski, Endwell, NY.

[73] Assignee: GAF Corporation, New York, NY.

[22] Filed: Dec. 20, 1972 [21] Appl. No.: 316,670

[52] US. Cl. 34/242, 68/5 E [51] Int. Cl. F26b 25/00 [58] Field of Search 34/l5, 155, 242; 432/242;

[56] References Cited UNITED STATES PATENTS 2,952,569 9/1960 Baer et al. 34/242 2,989,026 6/1961 Gardner et al 34/242 Primary Examiner-Kenneth W. Sprague Assistant Examiner-James C. Yeung Attorney, Agent, or Firm--W. C. Kehm; S. B. Leavitt [57] ABSTRACT ln an environmental chamber provided with a plurality of dynamic clearance seals disposed therein to enable the transferance of a web of material, i.e., film, through a separating wall without substantial leakage or contamination. Slotted ports offset 90 with respect to one another are disposed in the chamber entrance and exit to cooperate with corresponding clearance passages formed interior of the chamber and permits passage of the web material into more than one environment without contamination.

4 Claims, 2 Drawing Figures SEALING ARRANGEMENT FOR ENCLOSED CHAMBER The present invention is directed to a sealing means for positively sealing an environmental chamber in a manner enabling a web of material travelling therethrough, to be exposed to two or more noncommunicable atmospheric conditions. More particularly, the present invention is directed to a dynamic clearance seal employed in the transference of material through a barrier or separating wall, which barrier or separating wall seaparates two or more atmospheric conditions from one another.

It is quite common in the manufacture in certain types of materials such as films, sensitized papers, or other types of webs, to treat such webs or substrates in a series of progressive steps with solutions or atmospheres which are distinct from and have to remain isolated from one another. Failure to adhere to this procedure can result in: contamination of the various media being applied to the web of material; adverse and perhaps violent chemical reactions; poor quality control; etc.

The present invention is directed to a seal arrangement which is designed to confine a gaseous environment within a predetermined zone or section of a chamber where a web of material, such as film, must enter or exit. An obvious adjunct to the present invention is an arrangement for minimizing any leakage through the chamber wall such material passes.

Up until the present invention, a number of approaches have been employed in a sealing off of one environment from another; especially where different environments had to be used in the treatment or production of certain films. A most common approach in sealing off chambers included a seal in the form of a slot disposed in the chamber wall. In such embodiments, the slot had to be relatively large to prevent the film from touching the chamber wall in order to minimize friction or scratching of such film. Unfortunately, with this arrangement, a high gas leakage rate resulted and the system became less efficient as such leakage continued. lf friction and scratching were to be tolerated, then such slots were lined with a rubber or other suitable material. The lined material caused a wiping action. However, the resultant lower gas flow rates which took place adversely affected the entire operation.

Another approach included the use of two squeeze type rollers between which the film is drawn. Such roller arrangements were adapted to apply pressure to the film and in turn eliminate the leakage flow gap. The load applied by the rollers on the film had a tendency to damage the substrate of film materials, particularly if dirt particles were present and accumulated at the seal. With the aforementioned, the foreign particles tended to accumulate on the roller surfaces and in turn left imprints on the film. Also, the rollers were prone to rub the interface of the chamber wall and the rubber seal, thus creating another variable; excessive wear. The overall results of such prior arrangements were unsatisfactory, especially since they introduced friction and wear into the system.

Seals presently employed in systems where such environmental chambers are of particular utility are, for example, employed in Diazo film developing chambers containing ammonia, air and water vapor. The normal operating temperature for such a chamber is about 150 F although operation may occur over the range of from F to 200 F. The pressure differential between the atmosphere of the room and the chamber (pressure differential across seal) is about 0.02 inches of water. When employing a 1 inch diameter roller, a 0.018 inch annulus clearance, and a 1.38 inch film width, there is, for example, a resultant ammonia leakage of 0.8 cubic feet per hour for the inlet and outlet seals.

A principal feature of the present invention includes an environmental apparatus for a web of material requiring treatment with at least two non-contaminated atmospheres having integral sealed wall barriers, permitting such web material to travel into and out of housing without atmospheric leakage including: a housing; roller means disposed integral with respect to said housing proximate said points of entry and exit, for selectively engaging said material about the circumference thereof, permitting material travel in said housing; slotted ports integral with said housing being offset with respect to one another; and a clearance passage means disposed at points formed between said housing and the line of web travel defined by the disposition of said roller means.

Also with the scope of the present invention are structural features wherein the slotted ports are offset with respect to one another and the annular clearance passage formed between said housing and said line of film travel varies from 0.001 to 0.03 inches.

The instant invention contemplates usage where a pressure differential of less than 1.5 inches of water exists between the ambient atmosphere and the housing, as well as a relief means for minimizing the pressure differential.

Accordingly, it is the main object of the present invention to provide a sealing arrangement free from the defects of the prior art.

It is a further object of the present invention to provide a simple, yet reliable sealing arrangement which is free from the frictional or rubbing contact with the substrate travelling through the sealing arrangement.

It is a further object of the present invention to minimize the contamination of constituents, as by passing from one zone into the next, while at the same time minimizing the accumulation of such contaminates at the seal area.

Still another object of the present invention is to minimize any leakage from the chamber housing through the seals of the housing.

The aforementioned objects will best be understood with respect to the specification, claims, and accompanying drawings:

FIG. 1 is a chematic representation of a typical layout employing the concepts of the present invention with a web of film material.

FIG. 2 is a perspective detail of the sealing arrangement.

According to FIG. 1 as the web of film material 1 is drawn, it enters into an environmental chamber which is to be treated with a gaseous environment 2. Such ma terial is urged to travel through a seal arrangement 3 and is guided and threaded around suitable rollers such as tension rollers 4. Eventually, after being treated, the film material ultimately exits through still another seal disposed at 5 which is located at the point of exit in the chamber. Each of the aforementioned seals 3 and 5 respectively is provided with a roller 6 integral therewith which are seated in the sealing structure and are adapted to change the film material travel direction by 90 with respect to the point of entry. Furthermore, the roller in turn provides a means for controlling the sealing length; for example, alteration in the diameter of the roller 6 permits such an adjustment. The housing for the seals 3 and 5 respectively, can be designed to accomodate a range of roller wrap; that is, the amount of surface contact between the roller in the sealing arrangement and the wrap of the web of material passing therethrough can be effectively varied from 1 to 355. In turn, this relationship will vary in accordance with the amount of length of seal desired. Also, the arrangement as shown in FIG. I obviously can be varied as to number of seals, tension rollers, and the disposition of such seals.

FIG. 2 details the seal assembly in perspective. The roller 6 is mounted on a stationary shaft 7 within a close fitting housing structure 3,5. This entire arrangement is in turn disposed within the chamber housing 2 at points of entry and exit respectively, determined by the type of treatment to be employed on the web or type of substrate material entering and exiting. Suitable slots 8 are provided in the housing 3, where such slots are offset 90 with respect to one another for film to enter and exit from the housing 3. Such slots are shown in FIG. 1 as 8, 9 respectively and are likewise displaced 90 from one another. As film material 1 is fed into the housing through slots 8,9, it is urged to travel through an annular clearance shown as 10 in FIGS. 1 and 2. This clearance exits between the moving film material 1 and the housing 3, and some gas leakage does, in fact, occur at this point. This leakage is minimal, however, due to the restriction and frictional forces provided by the annular clearance which is controlled within prescribed tolerances. It should be understood that the volume or leakage flow through the area is obviously a function of the path length, width, height, pressure differential, viscosity of the fluids, etc. employed in the operation.

By way of example, it has been found that effective sealing can be provided with a film material to housing clearance of 0.001 to 0.03 inches. Such clearance allows dirt particle contamination which may be on the moving film material to pass through the clearance 10 without acting as an abrasive on such substrate. Also, in the event of momentary loss of tension, due to a malfunction or for other reasons, contact between the rollers 4 and the film housing 3 is minimized, thereby keeping damage to the film material at a minimum.

By way of example, the present invention has been found to function quite satisfactorily where the film speed entering and exiting from the chamber is governed by the components of the transport system, that is: film strength, bearing load, available power, etc.; and such speed can be varied accordingly. With the instant invention, the seal is intended to normally operate at a relatively low pressure differential. A change in pressure less than 1.5 inches of water has been found acceptable. However, higher pressures introduce a leakage rate which must be compensated by a reduced annular gap and thus the system can become quite impractical. The seal can be operated at any temperature which is compatible with the material employed in the seal or the film material moving through the chanber; also the seal may be employed to confine any gas, for example: air, ammonia, nitrogen, oxyden, etc., as long as such gas is compatible with the materials in the overall system.

By means of the arrangement as hereinbefore described, it has been found through empirical means that leakage is reduced substantially, i.e., up to 10 to l, as compared to a simple rectangular slots hereinbefore provided in the wall plates of the chambers. This feature is quite important, especially when handling materials which can react with the gases and especially after such gases have contaminated each other.

Another unique feature of the present invention resides in its capability of drawing off select gaseous leakage by means of a vacuum port, thereby preventing contamination of the second gas. To achieve this, a small vacuum port may be added to the exit slot and the vacuum can be adjusted for minimum pressure differential that is required to evacuate all the leakage. This arrangement is useful when even the slightest contamination or leakage cannot be tolerated.

It will be understood that certain changes may be made in respect to the size, dimensional relationships and construction without departing from the spirit and the scope as hereinbefore described.

What is claimed:

1. In an environmental apparatus for a web of nonmetallic material requiring treatment with at least two non-contaminated atmospheres'having sealed wall barriers, permitting such web material to travel into and out of a housing including: a housing roller means disposed integrally with respect to said housing proximate to said points of material entry and exit, for engaging said material about the circumference at an arcuate angle of from 1 to 355 thereof; slotted ports integral with said housing being offset with respect to one another for about and clearance passage means formed between said housing and the line of web travel defined by the disposition of said roller means enabling free material passage with minimum atmospheric leakage into and out of said housing.

2. In an environmental apparatus as claimed in claim 1 wherein: said annular clearance passage formed between said housing and said line of film travel varies from 0.001 to 0.03 inches.

3. In an environmental apparatus as claimed in claim 1 wherein: the pressure differential between ambient atmosphere and said housing is less than 1.5 inches of water.

4. In an environmental apparatus as claimed in claim 1, wherein: relief means are disposed at said exit slot to thereby minimize pressure differential between said ambient atmosphere and said housing. 

1. In an environmental apparatus for a web of non-metallic material requiring treatment with at least two non-contaminated atmospheres having sealed wall barriers, permitting such web material to travel into and out of a housing including: a housing roller means disposed integrally with respect to said housing proximate to said points of material entry and exit, for engaging said material about the circumference at an arcuate angle of from 1* to 355* thereof; slotted ports integral with said housing being offset with respect to one another for about 90*; and clearance passage means formed between said housing and the line of web travel defined by the disposition of said roller means enabling free material passage with minimum atmospheric leakage into and out of said housing.
 2. In an environmental apparatus as claimed in claim 1 wherein: said annular clearance passage formed between said housing and said line of film travel varies from 0.001 to 0.03 inches.
 3. In an environmental apparatus as claimed in claim 1 wherein: the pressure differential between ambient atmosphere and said housing is less than 1.5 inches of water.
 4. In an environmental apparatus as claimed in claim 1, wherein: relief means are disposed at said exit slot to thereby minimize pressure differential between said ambient atmosphere and said housing. 